The invention relates to a drive unit, in particular for a closing unit,
an injection unit or an ejector, an injection molding machine
according to the generic term
of claim 1.
Time is over,
injection molding machines
to be provided with electric and hydraulic drives, wherein over the
Electric drive with high speed positioning movements
comparatively small forces
the hydraulic drive is particularly advantageous when high axial forces at
Stelbewegungen must be applied.
Requirements occur, for example, in a closing unit
or an injection unit or when operating ejectors one
plastic injection molding machine
on. For example, for injecting plastic into a
a plasticizing screw with a relatively high axial velocity
Towards the shape moves to the shape completely with
is. During the
Nachdruckphase in which the molding loss by supplying
Compared to the molding compound, must via the injection unit a
high force without significant axial feed of the plasticizing screw
the requirements for a closing unit for closing the
Tool of an injection molding machine,
wherein the movable platen for closing the tool first on the
electric drive is moved quickly and then to complete retraction
and locking the tool with the required closing force only
a short rest stroke must be passed.
From the DE 101 21 024 A1
the applicant is a drive unit of an injection molding machine is known in which the comparatively large axial forces are applied during the closing of the injection mold or during the Nachdruckphase during injection via a hydraulic power booster. This hydraulic power booster has a piston unit with a comparatively small effective area, which is actuated via a spindle arrangement. The smaller piston unit delimited together with another piston unit with a larger effective area and an axially displaceable cylinder a pressure chamber. The cylinder can be locked to apply large axial forces, so that reduced by the axial movement of the smaller piston unit, the pressure chamber and according to the area difference between smaller and larger piston unit on the latter a high axial force on the unit to be acted (closing unit / injection unit / ejector) is applied. The axial fixing of the cylinder of the power booster takes place in the known solution in that a cylinder wall is bulged radially outward by the pressure increasing in the pressure chamber, so that the cylinder is fixed non-positively in a leadership of the cylinder and thus can no longer perform axial movement.
in this solution
is that the guide surfaces for the cylinder
on the one hand with regard to an optimal guidance and on the other hand however
also with regard to the positive locking of the cylinder
must be interpreted.
It must therefore be a compromise between optimal leadership and
good clamping effect can be found, so that the construction neither
on the fulfillment
one of the other function (terminals, guide) are optimally designed
In contrast, lies
The invention is based on the object, a drive unit for an injection molding machine
to create the leadership
and the frictional
Determining an intermediate part of a power converter of the drive unit
improved in the prior art.
Task is achieved by a drive unit with the features of claim
Drive unit according to the invention
has a force translator
with two relatively movable piston units with different effective surfaces. These
limit together with a displaceably guided intermediate part a pressure chamber.
To apply a large
Axial force is the intermediate part over
a clamping part on a support member supported on the frame of the injection molding machine
fixable. That the intermediate part positively locking elements - support / clamping part - are separated
from the leadership
formed of the intermediate part, so that these components optimally
to the respective task (guiding / clamping)
can be interpreted
and no functional compromises are required.
a preferred embodiment
has the supported on the frame of the injection molding machine support
a support anchor,
along which a radially deformable clamping sleeve is displaceable. These
is so in operative connection with the intermediate part, that at a
Setting the clamping sleeve
on the support anchor
Also, the intermediate part is locked in the axial direction.
radial deformation takes place in the clamping sleeve
preferably hydraulically over
the pressure applied in the pressure chamber. This is at a preferred
the invention, the clamping sleeve
received in a clamping cylinder whose annular pressure chamber via a
Pressure line is connected to the pressure chamber of the power converter.
the intermediate part and also the clamping sleeve or the clamping cylinder
preferably takes place via
a guide plate,
the Holmen of the injection molding machine
lies in a particularly simple construction embodiment
on the one hand on the clamping cylinder and on the other hand on the intermediate part.
Device-technical effort for the realization of the invention can be
further reduce when the support anchor
and / or the clamping sleeve
resiliently biased in the direction of their respective support position.
the guide plate
To lubricate, so that the life of the device over the conventional
when lubricating the guide
was not possible
was, otherwise the clamping effect would have been negatively affected.
Intermediate part of the force translator
is preferably carried out as a cylinder in which the pistons of
two piston units with smaller and larger effective area and
the pressure chamber are formed.
advantageous developments of the invention are the subject of further
In the following a preferred embodiment of the invention will be explained in more detail with reference to a schematic drawing. This shows a schematic sectional view of a closing unit of an injection molding machine. In the figure, only the upper half of the symmetrically constructed drive unit 1 shown.
The drive unit shown in the single figure 1 serves to actuate the closing unit of an injection molding machine, wherein a movable platen 2 should first be moved in the closing direction at a high speed (rapid traverse) and then run when the movable mold half on the clamped on a fixed platen mold half, the remaining residual stroke and the locking of the tool with great force.
The drive unit 1 has a force translator 4 , which is a piston unit 6 with smaller effective area and a force translator piston 8th having a larger effective area. A cylinder 16 of the force translator 4 is over a guide plate 10 at Holmen 12 guided on a rack 14 the injection molding machine are stored and on which also the movable platen 2 is stored. For applying large axial forces on the tool clamping plate 2 can the cylinder be 16 of the force translator 4 via a holding device 18 with reference to the frame 14 establish.
The operation of the force translator 4 takes place in the illustrated embodiment via a spindle drive with a spindle 20 , which is driven by an electric drive, not shown, with gear or belt drive. The axially fixed spindle 20 meshes with a spindle nut 22 , In the illustrated solution, the spindle drive is designed as a ball screw drive. The spindle nut 22 has a radially projecting support flange 24 on which a variety of pistons 26 the piston unit 6 are supported. Instead of several pistons 26 Also, a single piston can be used.
The right in the figure end portion of the piston 26 dives into a cylinder room 28 one, so this together with the associated piston 26 a partial pressure room 30 limited. The individual partial pressure rooms 30 of the force translator 4 are hydraulically connected to each other and are part of a pressure chamber, whose volume by axial displacement of the piston 26 is changeable.
According to the figure, the cylinder surrounds 16 the spindle nut 22 and lies with an abutment shoulder 32 on the end face of the support flange 24 at. In the area of this contact shoulder 32 is in the cylinder 16 a clutch 34 , Preferably provided an electromagnetic clutch, via which the cylinder 16 to the spindle nut 22 can be coupled, so that their axial displacement on the cylinder 16 is transmitted.
In the from the clutch 34 remote end portion of the cylinder 16 is an annulus on the front side 36 formed in which a guide section 38 the executed as a hollow piston force translator piston 8th is guided. This limits with the annulus 36 a force translator room 40 that is via a pressure line 42 with the partial pressure chambers 30 connected so through this and the power translator room 40 the pressure chamber of the force translator 4 is formed.
The from the leadership section 38 Remote annular face of the power transmission piston 8th engages directly or indirectly on the movable platen 2 at. The power transmission piston 8th is about one in the annulus 36 arranged and at the guide section 38 attacking spring 44 in the direction of a minimum volume of the force translator chamber 40 biased.
According to the picture, the cylinder has 16 at its right end portion a radially projecting driving shoulder 46 at which the cylinder 16 encompassing guide plate 10 is supported in the axial direction.
In the illustrated embodiment, the guide plate 10 one or more to its central axis 48 staggered recesses 50 , in each case a clamping cylinder 52 the holding device 18 is used. It is preferred, more of the clamping cylinder 52 to distribute around the circumference; in principle, at lower closing forces, a single clamping cylinder 52 sufficient, but then coaxial with the cylinder 16 should attack.
The clamping cylinder 52 dives with a reclassified end section 54 into the recess 50 the guide plate 10 one. On the end section 54 of the clamping cylinder 52 is a spring 56 , For example, a disc spring assembly mounted on the one hand to a ring 58 is supported and on the other hand on the guide plate 10 attacks, leaving the clamping cylinder 52 with a shoulder 60 against the guide plate 10 is biased. The recess 50 is with a certain play to the outer circumference of the end portion 54 of the clamping cylinder 52 designed so that over the spring 56 a certain adjustment of the axial position (axis 62 ) of the clamping cylinder 52 is possible.
In this clamping cylinder 52 is a clamping sleeve 64 used in common with the jacket of the clamping cylinder 52 an annulus 66 limited, via a connecting channel 68 with the partial pressure chambers 30 connected is. In the illustrated embodiment, the connection channel extends 68 from the cylinder 16 over the guide plate 10 in the clamping cylinder 52 into it. The annulus 66 is about sealing arrangements 70 . 72 sealed to the outside. The clamping sleeve 64 is designed so that when applying the annulus 66 is deformable with a predetermined minimum pressure in the radial direction and thus on a support armature 74 can be clamped. This positive connection is designed such that the support forces resulting from the locking force can be transmitted.
The clamping sleeve 64 surrounds the rod-shaped support anchor 74 , whose in the figure right end section also the guide plate 10 interspersed. The support anchor 74 is one-sided on a support device 76 on the frame 14 the injection molding machine supported. In the illustrated embodiment, the support means 76 one on the rack 14 anchored support bracket 78 at which a biasing spring 80 is supported. This attacks on a support ring 82 on, on the support anchor 74 is attached and there for example via a spring washer 84 is supported in the axial direction. About the preload spring 80 becomes the left end face of the support anchor in the figure 74 against a contact surface 86 of the frame 14 biased.
The resilient positional positioning of the support anchor 74 and the clamping cylinder 52 allows easy compensation of manufacturing tolerances, as the springs centered along the common axis 62 allow.
The feathers 56 . 80 must be designed so strong that when opening the forces occurring due to friction on the mold and in the leadership can be overcome.
In the illustrated embodiment, a plurality of pistons 26 used. Instead of these pistons, a single hollow piston can be used, the annular end face a much smaller effective area than that in the annulus 36 recorded end face of the power transmission piston 8th Has.
For a better understanding, the function of the drive unit 1 explained.
It is assumed that the clamped on the tool clamping plate tool is open, wherein the cylinder 16 When the tool is open, either the position shown is occupied or even further to the left in contact with the frame 14 is moved.
To close the tool in rapid traverse, the first clutch 34 indented so that the cylinder 16 with the spindle nut 22 connected is. At the same time the drive motor of the spindle 20 controlled and this set in rotation, so that the spindle nut 24 Corresponds to an axial feed to the right (illustration). The cylinder 16 is about the clutch 34 taken along, leaving the entire force translator 4 moved to the right and the platen 2 is moved in the closing direction. This closing movement takes place at a comparatively high speed, wherein only a small force is to be transmitted via the spindle drive.
During this axial displacement in rapid motion, the volume of the partial pressure chambers changes 28 and the force translator room 40 ge formed pressure chamber of the cylinder 16 not, so that accordingly the pressure in the pressure chamber remains constant.
When closing the tool is to apply a high clamping force the clutch 34 solved so that the cylinder 16 no longer of the spindle nut during the rest of the remaining stroke 22 is taken. This will immerse the pistons 26 in the cylinder chambers 28 a, so that the volume of the partial pressure spaces 30 is reduced and according to the pressure in the pressure chamber of the cylinder 16 increases.
To evade the cylinder 16 To prevent to the left, this is about the holding device 18 clamped. In the illustrated embodiment, this is done by the clamping sleeve 66 through the in the pressure room (partial pressure chambers 28 , Force translator room 40 ) increasing pressure, which over the connecting channel 68 also in the annulus 66 abuts radially inwardly deformed and positively on the outer circumference of the support rod 74 is determined. The preloaded spring 44 ensures that a clamping force is built up before the closing force occurs. The clamping effect is sufficient to the cylinder 16 To set the locking force in the axial direction. Due to the increasing pressure in the pressure chamber 68 becomes the power transmission piston 8th that has a much larger effective area than the pistons 26 has acted in response to the area ratio of the active surfaces with a large force in the closing direction of the tool, wherein the stroke is carried out in accordance with reduced speed.
During the entire closing movement and during the construction of the locking force is the cylinder 16 over the guide plate 10 exactly on the rigid bars 12 guided. The from the power translator 4 by the pressure in the force translator room 40 generated, acting on the movable tool half supporting force is on the cylinder 16 , the driving shoulder 46 , the guide plate 10 and over his shoulder 60 on the clamping cylinder 52 and continue over the clamping sleeve 64 on the support anchor 74 transferred and over the contact surface 86 in the frame 14 introduced the injection molding machine, so that a secure locking of the tool is ensured even at high closing forces.
The construction according to the invention is characterized by an extremely simple construction, wherein the loose mounting of the support anchor 74 and the clamping cylinder 52 with preloaded springs 80 . 56 high tolerances on the construction can be avoided. The requirements for these springs 56 . 80 are comparatively small, since they only need to transfer the frictional force and the forces to drive the tool.
Because the leadership of the cylinder 16 Functionally separated from the clamp, the guides between the guide plate 10 and the spars 12 be lubricated in an optimal way. With fixed cylinder 16 are the deformations of the spars 12 minimal as the geometrical accuracy of the fixture 18 is very high and the clamping cylinder 52 and the support anchors 74 through the loose storage optimally to each other and to the spars 12 are adjustable.
illustrated one-sided storage of the components allows the
further a good accessibility
the drive unit and a simple assembly and disassembly, so
that maintenance is easier.
is a drive unit, in particular for a closing unit,
an injection unit or ejector, an injection molding machine,
at the big one
Axial force over
a hydraulic power booster
can be applied. A cylinder of the power translator can be
determine with respect to a frame of the injection molding machine via a holding device,
the functionally separated from the leadership of the cylinder on the frame
the injection molding machine
- drive unit
- Power transmitter
- piston unit
- Power booster piston
- guide plate
- spindle nut
- support flange
- cylinder space
- Part-pressure chamber
- contact shoulder
- guide section
- Power booster chamber
- pressure line
- driving shoulder
- central axis
- clamp cylinders
- connecting channel
- sealing arrangement
- sealing arrangement
- support anchors
- support means
- support bracket
- biasing spring
- support ring
- spring washer
- contact surface